Isis fighters on the border between Syrian and Iraq in June 2014.
Photograph: Medyan Dairieh/ZUMA Press/Corbis

Islamic State’s incursions in Iraq and Syria have left large areas of both countries under the militant group’s control. The extremists’ beheadings of western hostages have sparked outrage across the world. Since its military successes, other jihadi groups have flocked to affiliate themselves with the radical movement.

Iraq

Born out of al-Qaida in Iraq – which emerged during the US occupation – Isis now controls vast swaths of the country’s Sunni heartland. The militants launched a lightning offensive last summer in which they conquered the province of Nineveh and its capital, Mosul, Saddam Hussein’s hometown of Tikrit, and large parts of Anbar province, from which it had once been evicted by the US-backed Sunni “Awakening” movement.

Isis lost Tikrit in an operation this year led by a volunteer army dominated by Shia militias with close ties to Iran, but the militants demonstrated their resilience by conquering Ramadi, 80 miles west of Baghdad, in May. The US has sent hundreds of military advisers and led a coalition conducting regular air strikes against the group, but has so far failed to stem the militants’ advance.

Syria

Isis now controls roughly half of Syria’s landmass and the city of Raqqa is the capital of its self-proclaimed caliphate. Territories held include most of Raqqa and Deir ez-Zor provinces in the north-east and east of the country, areas around the cities of Aleppo and Homs (including the historic city of Palmyra), as well as parts of southern Damascus, where it recently seized the besieged Yarmouk Palestinian refugee camp. The group has fought against all sides in the civil war: Syrian rebels, troops loyal to the Assad regime, Kurdish militias and even the al-Qaida affiliate in Syria, Jabhat al-Nusra. It split from al-Nusra in 2013 after the group’s leader refused to pledge allegiance to the Isis chief Abu Bakr al-Baghdadi. Syria is where Isis suffered its most devastating defeat, when an ill-fated advance on the border town of Kobani was met by fierce Kurdish resistance and intense aerial bombardment by the US-led coalition. Isis lost nearly 2,000 fighters. An alliance of Kurdish miltia and opposition fighters has recently dealt Isis a series of defeats in northern Syria, conquering territory including the key border town of Tal Abyad, a source of foreign fighters and supplies.

Egypt

A group called the Province of Sinai (once known as Ansar Beit al-Maqdis) emerged in the aftermath of the uprising that ousted Egypt’s autocrat Hosni Mubarak. Its attacks have become more ferocious since the removal of Mohammed Morsi, the Muslim Brotherhood-backed president, in 2013, and it pledged allegiance to Baghdadi late in 2014.

The Sinai-based group has attacked the Egyptian army as well as targets in Cairo. This week it launched a series of coordinated assaults on army positions near the towns of Sheikh Zuweid and Rafah. In the most significant escalation in the peninsula in years, F-16s and Apache helicopters were deployed by the government of Abdel Fatah al-Sisi, which the insurgency seeks to topple.

Yemen

Isis has had a limited presence in Yemen compared to al-Qaida in the Arabian Peninsula, the jihadi network’s most powerful franchise, but it has claimed a number of devastating attacks in recent months, primarily targeting Yemeni Houthis – who belong to the Zaydi sect of Shia Islam – including a double suicide bombing of two mosques in March that killed more than 100 worshippers. Isis considers Shias heretics.

Isis stands to benefit from the chaos in Yemen, which is engulfed in a debilitating civil conflict and blockade. A Saudi-led coalition launched an air campaign in March against the Iranian-backed Houthis, who took control of the capital, Sana’a, last year and advanced on the country’s south, exiling the Saudi-backed president.

Cars destroyed by a bomb outside the Green Dome mosque on 17 June 17 in an attack reportedly claimed by Isis. Photograph: Sebastiano Tomada/Getty Images

Gulf states

An Isis affiliate called the Najd Province, named after the central region of Saudi Arabia, has claimed responsibility for recent bombings in Saudi Arabia and Kuwait that have primarily targeted Shia communities in an attempt to sow greater sectarian tension.

Last week a suicide bomber detonated an explosive vest in a Shia mosque at the centre of Kuwait City, killing more than two dozen worshippers, in the country’s worst terrorist attack in years. One-third of Kuwait’s population is Shia. Isis has also claimed responsibility for attacks on Shia mosques in May in Dammam and Qatif, Saudi Arabia. Isis despises the Gulf monarchies.

Afghanistan and Pakistan

Isis declared the creation of the “Khorasan province” earlier this year, referring to a region spanning parts of Pakistan and Afghanistan and making inroads into Taliban territory, with foreign fighters loyal to it recruiting local fighters. The group has attacked Taliban positions in recent weeks and months, including beheading 10 Taliban fighters in June and seizing territory from their militant rivals.

Isis claimed its first major attack in Afghanistan in April with a suicide bombing in Jalalabad that killed dozens of people. The Taliban published a letter last month urging Isis to stay out of Afghanistan.

Dagestan

Insurgents based in the northern Caucasus region in Russia have pledged allegiance to Isis and declared the so-called Vilayat Dagestan. The militants once belonged to the Caucasus Emirate, a jihadi group that has claimed bombings in Moscow.

Libya

Ansar al-Sharia, one of the largest militant groups in the country, which was blamed in 2012 for the killing of the US ambassador to Libya, has rebranded itself as Isis in Benghazi, Sabratha and Sirte. The group’s key territory in the country, which has descended into chaos following a power struggle between Islamists and their elected successors, is the city of Sirte and the surrounding villages and oil fields. The militants were pushed out of the city of Derna last month in battles with rival Islamist groups.

Small units have battled the Libyan army in Benghazi and have carried out attacks in the capital, Tripoli, including one in January targeting the Corinthia hotel. The affiliate has released videos depicting the beheadings and shootings of Coptic Christians from Egypt and Ethiopia kidnapped by the militant group in Libya in recent months.

Tunisia

British and Irish tourists pray together in front of a memorial to the Sousse victims. Photograph: Chris Stephen for the Guardian

Fighters from Tunisia account for one of the largest per capita contributions to Isis’s foreign contingent in Syria and Iraq, with the government estimating their number at 3,000. Inside Tunisia, groups operate as cells in towns and cities, mostly south and south-west of Tunis, with the army fighting intermittent battles with jihadi groups criss-crossing borders with Libya and Algeria.

Kairouan, the home of the gunman who massacred tourists in the beachside city of Sousse last week, is an important jihadi recruitment centre. Isis has claimed responsibility for the attacks in Sousse and the Bardo museum in Tunis this year in statements on social media, though their authenticity has not been verified.

West Africa

The insurgent group Boko Haram pledged allegiance to Isis in March, a declaration that has been accepted by Isis in an effort to spread the influence of its self-proclaimed caliphate in west Africa. The group, which was formed in the early 2000s in to impose sharia rule in northern Nigeria, has slaughtered thousands and carried out hundreds of kidnappings in attacks that have spread to neighbouring Chad and Niger.

Boko Haram suicide bombers killed dozens of people in attacks in Chad’s capital, N’Djamena, in June, and the militant group is believed to have committed another massacre in Borno this week, killing 150.

Bosnia

Isis has recently begun attempting to recruit fighters from among poor and unemployed youth in the Balkans, with Bosnia and Herzegovina a particular focus. A recent video featured Bosnian fighters urging their countrymen to join the group.